The present invention relates to a leaf-spring coupling, and particularly one that is torsionally elastic. Such couplings comprise an inner coupling part or hub, an outer coupling or ring, and radially extending leaf-spring assemblies that elastically join the inner and outer coupling parts. Upon relative motion or turning between the two coupling parts, the leaf-spring assemblies are stressed.
In one known coupling of this type, shown in Kupplungs-Atlas, 1975, pages 41 to 40, A.G.T.-Verlag Georg Thumm, Ludwigsburg, the leaf-spring assemblies are clamped to the outer ring using intermediate pieces which extend between the leaf-spring assemblies in the direction toward the hub. The radially inner ends of the intermediate pieces have stop surfaces, which, at the maximum angle of intended turn in each case, strike against those leaf springs which engage into the hub, and therefore against the so-called principal springs. The end stop thus formed is hard, and the principal springs thereby have extensive shear stress applied to them. Accordingly, there is the danger that the principal springs may break under strong torsional blows.
Up to the end stop, the torsional stiffness of the known coupling is constant, i.e. its torsion characteristic increases linearly. Frequently, however, it is necessary for the torsional stiffness of the coupling to increase progressively as the angle of turn increases. For this purpose, there is a known coupling in which only a few of the leaf-spring assemblies that project from one of the coupling parts continuously engage the other coupling part. The other leaf-spring assemblies engage that other coupling part only after a given angle of twist between the coupling parts. In this way, a torsion characteristic is produced which has two linear regions of different pitch. This torsion characteristic already approaches a progressive characteristic and can be referred to as a "graded progressive characteristic." The grading, however, is still very coarse. Vibrational problems can result. Furthermore, it is unsatisfactory that a few leaf-spring assemblies participate only part of the time in the transmission of the torque. The other leaf-spring assemblies have no effect at an angle of turn below the angle of turn at which they initially engage.